DATA RECORDING MEDIUM AND ELECTRONIC DEVICE USING THIS MEDIUM

Abstract: Security is maintained not by judging coincidence to a special code or an exclusive IC chip but by judging coincidence to a particular indication such as a trademark which has been socially recognized and of which the imitation has been banned. A CD-ROM (17) is loaded in a game machine (10) to play a game using programmed data stored in the CD-ROM (17). The game machine is provided with a recognition sensor (22) for reading the trademark (20) on the surface of the CD-ROM (17), and a judging unit (26) that judges whether the trademark (20) read by the sensor (22) agrees with a particular trademark TM. If they do not agree, the game will not start.

Description: TECHNICAL FIELD The present invention relates to an information storage medium which stores information of game programs etc., and an electronic device for reading and utilizing the information stored in the information storage medium; and more specifically to a CD-ROM and game machines for optically reading program information stored in the CD-ROM and for executing games. BACKGROUND ART Various amusing computer game software has been developed for home video game machines with which various games can be played by changing CD-ROMs. Such video games are very popular for amusement. Sometimes, the supply of popular game software does not catch up with the demand, and CD-ROMs carrying game software are traded at high prices. Counterfeits of such CD-ROMs are continually being discovered. Producers of game software have made various security systems to prevent counterfeiting of game software which is the fruit of development by producers with considerable investment of money, time and effort. In one such security system, the agreement of data, such as a special code incorporated into program information read from a CD-ROM, with data stored in advance in a main body of a game machine is judged to allow access to the CD-ROM. However, in such conventional security systems, where security depends on the agreement between program information stored in a storage medium and data stored in a main body of a game machine, security would be unavoidably breached if the security data were decoded. Once security is breached, means for excluding counterfeits are limited, which makes it difficult to effectively exclude counterfeits from the market. Known security systems for overcoming such disadvantages are described in Japanese Patent Laid-Open Publication No. 101349/1983, U.S. Patent No. 4,454,594, U.S. Patent No. 4,442,486, U.S. Patent No. 4,462,076 and others. In the security systems disclosed by the known art, a coded identifier indicative of a trademark, copyright or the like, is stored in a program memory in a video game cartridge, and a reference identifier is stored in a computer system in a video game machine. When the cartridge is loaded into the video game machine, the reference identifier in the video game machine is compared with the identifier read from the program memory. When the comparison finds agreement between the reference identifier in the video game machine and the identifier in the program memory, the identifier, e.g. a trademark, copyright or the like, is displayed on a monitor display. When there is no agreement, the operation of the video game machine is stopped, preventing the execution of the program. For a counterfeiter to supply a program operative on such video game machines, it is necessary to incorporate a coded identifier corresponding to a trademark, copyright or the like which agrees with a reference identifier stored in advance in authentic game machines. This is an infringement, in principle, of proprietary rights, such as trademarks, copyrights or the like. In a conventional security system, unless a counterfeiter displays a trademark, copyright or the like corresponding to a reference identifier visibly on the exterior surface of, e.g., a cartridge, legal accusation is difficult, as property right infringement is based only on visually observed trademarks, copyright or the like. Hence, conventional security systems are at a disadvantage and make it difficult to seek protection under trademark acts, intellectual property laws, etc. Prior art document BE-A-1005263 discloses a security system similar to those described above, except that a security code is recorded on the exterior or on the housing of the data storage medium, independently of the main data storage region of the medium. This allows the security code to be read without risk of infecting the computer with a virus and also allows the media to be personalized by the user for use with a specific computer. Document EP-A-0378385 is an example of the previously discussed prior art, in which a copyright message from a games cartridge is compared with reference data stored in the game apparatus. However, the copyright message is not stored in a form recognizable by the human eye. Document EP-A-0545472 discloses a copy protection system for a disk, in which information is stored using pits. A security code is stored as a variation in a second physical parameter of the pits, such as their width or lateral displacement, which will not generally be included in any unauthorized copy of the disk. There is no suggestion that the variations in the second physical parameter should be recognizable to the human eye. Document GB-A-2250626 discloses a method of manufacturing a disk in which information is stored using pits. In regions that do not store information, an array of pits may be formed that is legible to the human eye. However, there is no suggestion that the legible array may also be read by the electronic device; and no security implications are discussed. US-A-4967286 discloses a similar system. A first object of the present invention is to provide an information storage medium incorporating a novel security system which can effectively exclude counterfeits or unauthorized copies and an electronic device using the same. A second object of the present invention is to provide an information storage medium which can effectively exclude counterfeits even when its security system is deciphered and an electronic device using the same. A third object of the present invention is to provide an information storage medium which can effectively exclude counterfeits, and an electronic device using the same. A fourth object of the present invention is to provide an information storage medium which can easily detect a specific indication in a security system, and an electronic device using the same. DISCLOSURE OF INVENTION The electronic device according to one embodiment of the present invention comprises an authentication system wherein the authenticity with respect to the electronic device of an optical disk is checked, wherein the authentication system comprises reference information stored in advance in the electronic device, a disk mounting means on which the optical disk is to be mounted, detection means for detecting authentication information from the optical disk and comparison means for comparing the detected authentication information with the reference information, wherein the said detection means are arranged to detect a specific indication as the authentication information from a predetermined region of the optical disk; characterized in that the specific indication is also recognizable by the naked human eye as a proprietary indication, the proprietary indication being of a nature that unauthorized use of the proprietary indication is legally prohibited. According to this embodiment, when a counterfeiter supplies optical disks intended to operate on an authentic electronic device, he has to illegally display the visible proprietary indication corresponding to said reference signal on the surface of each counterfeit disk, whereby counterfeits can be more effectively excluded from the market. The invention also provides an information storage medium comprising an optical disk containing a first region in which software information is stored so that when the optical disk is mounted on an electronic device, the software information is optically read by detection means provided in the electronic device, characterized in that the optical disk medium further comprises a second region disposed in a region different from the said first region, the second region contains a specific indication formed by means of pits so that the specific indication formed by means of pits is detectable by the said detection means and can be judged as authentication information by comparing the information detected from the specific indication with a reference information stored in advance in the electronic device as well as recognizable by the naked human eye as a proprietary indication, the proprietary indication being of a nature that unauthorized use of the proprietary indication is legally prohibited. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block diagram of a game machine according to a first embodiment of the present invention. FIG. 2 is a perspective view of the main body of the game machine. FIG. 3 is a plan view showing a CD-ROM for use with the invention in FIG. 1. FIGs. 4A and 4B are explanatory views of the recognition sensor in FIG. 1. FIG. 5 is a flow chart of the operation of the game machine of FIG. 1. FIG. 6 is a block diagram of the game machine according to a second embodiment of the present invention. FIG. 7 is a plan view of the CD-ROM in FIG. 6. FIG. 8 is a partial sectional view of a major part of the CD-ROM of FIG. 6. FIG. 9 is a flow chart showing the operation of the game machine of FIG. 6. FIGs. 10A to 10D are plan views of variations of the CD-ROM of FIG. 6. FIGs. 11A to 11C are explanatory views of a specific method for forming a specific indication with pits on a CD-ROM. BEST MODE FOR CARRYING OUT THE INVENTION The game machine according to a first embodiment of the present invention will be explained with reference to FIGs. 1 to 5. As shown in FIGs. 1 and 2, the main body 10 of the game machine includes a control unit 10a and a CD-ROM control unit 10b. The control unit 10a is provided with a game control unit 11 for controlling games, an output interface 12 for supplying audio and video signals, input interfaces 13a, 13b for receiving operation or manipulation signals, and input/output interfaces 14a, 14b, 14c for receiving/supplying the program and data for executing games. The output interface 12, the input interfaces 13a, 13b, and the input/output interfaces 14a, 14b, 14c are all connected to the game control unit 11. As shown in FIG. 1, the control unit 10a is connected to a television unit 15 employed as a display unit for displaying the contents of a game via output interface 12. The control unit 10a is also connected to various controllers, e.g. joy pads 16a, 16b for manipulating play of the game, via input interfaces 13a, 13b. The main body 10, the television unit 15, the joy pads 16a, 16b, etc. constitute the game machine. As shown in FIG. 2, a CD-ROM mount 18 for mounting a CD-ROM 17 (an optical information storage medium) to be removably mounted is formed on the top surface of the CD-ROM control unit lOb. The CD-ROM mount 18 is covered by a lid 19 which can be opened and closed. After the CD-ROM 17 has been put on the CD-ROM mount 18, the mount 18 is closed by the lid 19 to cover the CD-ROM 17. As shown in FIG. 3, the CD-ROM 17 is a thin disc with a center hole 17a in the center thereof. In the present embodiment, the CD-ROM 17 stores digital information, e.g. a game program, data, etc., with pits. The underside of the CD-ROM 17 is the optical detection surface, through which the pits in the CD-ROM 17 are detected by laser beams. On the upper surface of the CD-ROM 17, opposite to the underside, a title 17b of the game, a design 17c, a trademark indicative of the manufacturer of the game, etc. are indicated. The trademark etc. are indicated in a trademark indication region 20 near the outermost periphery. In this specification, the trademark indication region 20 may be called "a predetermined portion" or "a predetermined region". In the CD-ROM mount 18, an optical pickup 21, which is an information detecting means, is located so as to face the underside of the mounted CD-ROM 17, which is the optical detection surface. The optical pickup 21 is disposed to be radially movable over the underside of the disc 17. The optical pickup 21 reads program information from the CD-ROM 17 as it is rotated by a drive motor. The optical pickup 21 is connected to the input/output interface 14c of the main body 10. The program information read by the optical pickup 21 is supplied to the game control unit 11 via the input/output interface 14c. When the CD-ROM 17 is thus placed on the mount, the game machine operates and images are displayed on a screen 15a of the television unit 15 while the joy pads 16a, 16b are operated to play the game. The CD-ROM 17 is replaced by a different CD-ROM storing different program information to play a different game. The main body 10 can reproduce music, information, etc. from data stored on various CDs. Music can be listened to from speakers 15b of the television unit 15, and visual information can be viewed on the television screen 15a. On the backside of the lid 19, a recognition sensor 22 is provided for reading the trademark indication region 20 of the CD-ROM 17 mounted on the CD-ROM mount 18. When the lid 19 is closed after the mounting of the CD-ROM, the recognition sensor 22 is situated opposite to the trademark indication region 20. As shown in FIGs. 4A and 4B, the recognition sensor 22 has a base 23 which extends radially over the exterior surface of the CD-ROM 17, covering the length of the trademark indication region 20. As shown in FIG. 4A, the surface 23a of the base 23 has a plurality of light emitting portions 24 disposed in the radial direction of the top surface of the CD-ROM 17, and a light detecting portion 25 disposed linearly also in the radial direction. One or a plurality of the light emitting portions 24 are disposed as required. The light emitting portions 24 and the light detecting portion 25 are so arranged that light emitted from the light emitting portion 24 is reflected by the trademark indication region 20 to be incident on the light detecting unit 25. As seen in FIG. 4B, the light emitting regions 24 and the light detecting region 25 are tilted with respect to each other on both ends of the concave surface 23a. Accordingly, a path drawn by tracing out along the trademark indication region 20 of the CD-ROM 17 upon rotation is always within the range of recognition of the recognition sensor 22. Thus, when the CD-ROM 17 is placed on the CD-ROM mount 18, and the mount 18 is closed by the lid 19, the recognition sensor 22 can read a trademark on the trademark indication region 20. The read-out signal of the trademark is supplied to a judgement unit 26 in the control unit 10a through the input/output interface 14b. The recognition sensor 22 may instead be disposed on an extension (not shown) of the main body 10 over the CD-ROM mount 18 so as again to be opposite the CD-ROM 17. The CD-ROM 17 is inserted below the extension so as not to touch the extension. The extension is located at a position where it will not interfere with mounting and removing the CD-ROM 17 and in a position where the recognition sensor 22 can recognize the trademark indication region 20. The recognition sensor 22 may be located on the forward end of a retractable arm (not shown) which is positioned in the main body 10 and can extend to the CD-ROM mount 18. This arm automatically extends over the CD-ROM 17 into a position where the trademark indication region 20 can be recognized when the CD-ROM 17 is mounted. Thus, the arm does not hinder mounting and removing the CD-ROM 17. The judgement unit 26 compares a signal corresponding to the trademark detected by the recognition sensor 22 with trademark information stored beforehand as a reference in the main body 10, and outputs an agreement or disagreement signal. The information stored beforehand as the reference in the judgement unit 26 is not limited to a trademark and may be a specific indication that can be legally protected, e.g. a design such as a game character, a tradename or the like. It is preferable that use of the specific indication by an unauthorized person is prohibited. The specific indication by the manufacturer of the game machine itself may be owned or licensed from another entity and may be a combination of a plural number of the same indication or of different indications. The agreement or disagreement signal from the judgement unit 26 is supplied to the game control unit 11. When an agreement signal exists and is input to the game control unit 11, security is cleared and the program of the CD-ROM 17 is supplied to the game control unit 11. On the other hand, when a disagreement signal exists and is input to the game control unit 11, security is not cleared and supply of the program information of the CD-ROM 17 to the game control unit 11 is blocked. When the game control unit 11 receives a disagreement signal, it executes an error processing routine which, for example, outputs a warning signal to display a warning, such as "This disc cannot be used", on the screen of the television unit 15, or a stop signal for stopping the operation of the main body 10. From such error processing, operators of the game machine know that the CD-ROM 17 with an unauthorized specific indication cannot be used. As shown in FIG. 1, in addition to CD-ROMs 17, game cartridges of semiconductor ROMs and RAMS storing game programs can be used as the information storing media for the main body 10. In such case, as shown in FIG. 2, a cartridge 27 is inserted into the cartridge mount 28 of the control unit lOa, thereby supplying game program information to the game control unit 11 through the input/output interface 14a. The operation of the game machine according to the present embodiment will be explained with reference to the flow chart of FIG. 5. First, a disc, such as a CD-ROM 17 storing a game program is placed on the CD-ROM mount 18, and the lid 19 is closed. The disc is thus mounted on the main body 10. The main body 10 can reproduce music or other information from data stored in the CD, e.g. a musical CD or data information CD, mounted thereon. The optical pickup 21, and the recognition sensor 22 are then ready for actuation. The disc drive is actuated, and the mounted disc is rotated (Step S1). When the disc starts rotation, the optical pickup 21 picks up TOC (Table of Contents) information from the innermost circumference of the disc (Step S2). If the optical pickup 21 fails to read this information, Step S2 is repeated. The TOC is read to judge whether or not the mounted disc is a musical CD (Step S3). If the disc is a musical CD, Step S4 follows to reproduce the music. When the disc is other than a musical CD, Step S5 follows to judge whether or not security has to be checked in reproducing the disc, i.e., whether or not the disc holds a game software information requiring judgement as to whether it is authentic or counterfeit. When a security check is required, Step S6 follows, and the recognition sensor 22 reads the trademark indication region 20 which should indicate a specific trademark on the CD-ROM 17. When a security check is not required, Step S7 follows to judge whether the disc is a general purpose disc. Information read by the recognition sensor 22 is supplied to the judgement unit 26, and the judgement unit 26 conducts pattern matching in which the read information is compared with specific trademark information stored beforehand as a reference to judge whether the read information agrees with the specific trademark information (Step S8). When the specific trademark is recognized, i.e. when the judgement unit 26 judges that the read information agrees with the reference information, Step S9 follows. Security is cleared and program information in the CD-ROM 17 is transmitted to the game control unit 11 for game processing there. When the specific trademark is not displayed in the predetermined region of the disc, Step S10 follows. Security is not cleared and error processing, such as a warning display or the like, is conducted. In Step S7, when the information stored in the disc is general software other than game software, Step S11 follows to conduct play processing. For example, when the disc is a data information CD, read data is displayed on the monitor. When the information is not general software, i.e. the disc holds data in a format that is incompatible with the main body 10, error processing, such as a warning display or the like, is conducted (Step S12). Thus, conventional security systems have employed a process of judging agreement with a specific code or the like. In the game machine according to the present embodiment, the agreement of a visual indication, such as a trademark or the like is judged for security. As the visual indication can be used an image such as a trademark which is widely recognized for its originality and invariably indicated on CD-ROMs. Such an image can effectively hinder counterfeiting, thereby enhancing security. In the case where musical and data information CDs require security, the present invention is applicable as to game software CD-ROMs, and can also effectively exclude counterfeits. The game machine according to a second embodiment of the represent invention will be explained with reference to FIGs. 6 to 9. Elements common to the first embodiment and the second embodiment are indicated by common numerals. A game machine 29 according to the second embodiment reads with an optical pickup 21 through an optical detection surface a trademark indication region 30 formed at an information storage area. The trademark indication region is formed not on the upper surface of a CD-ROM 17 but rather in the storage area of the CD-ROM 17. Trademark information in the predetermined region can be read without additionally providing the recognition sensor 22 as in the game machine according to the first embodiment. As shown in FIG. 6, the game machine 29 comprises a control unit 29a, and a CD-ROM control unit 29b which obtains trademark information via an optical pickup 21 in place of the recognition sensor 22. In the control unit 29a an input/output interface 14b connected to the optical pickup 21 is connected to a game control unit 11 through a judgement unit 26. The rest of the game machine 29 has the same construction as the game machine according to the first embodiment. The optical pickup 21 reads program information stored in the CD-ROM 17 and also reads a specific indication stored in the trademark indication region 30. That is, the optical pickup 21 functions as an information detecting means which detects both the information region of the CD-ROM 17 and a predetermined region of the CD-ROM 17. In the present embodiment, as shown in FIG. 7, the trademark indication region 30 is formed to be visible through a transparent plastic substrate 31, the optical detection surface of the CD-ROM 17. As shown in FIG. 7, a program region 32 in which program information for a game is stored with pits is formed on the plastic substrate 31 between a read-in region 32a and a read-out region 32b. In the program region 32, a trademark indication region 30, in which the game program information is not stored, is formed over about 100 - 200 tracks adjacent to the read-in region 32a. In the trademark indication region 30, a visible trademark TM is formed using a group of pits. When the optical pickup 21 reads the trademark indication region 30, the location of which is indicated by TOC information, the trademark TM is detected as security check information, and its shape can be visible from the optical detection surface. A shown in FIG. 8, on the upper surface 33 of a plastic substrate 31, the CD-ROM 17 stores game program information using a group of pits, and has the trademark indication region 30 formed thereon. The substrate can be of polycarbonate, acryl, polyvinylchloride or others. The top surface 33 with the pits formed thereon is covered with a reflection layer 36 of metal such as aluminium and further with a protection layer 37, whereby an exterior surface 38 is constituted. Usually the protection layer 37 is formed of a transparent material, and a title 17b of a game software program, a design 17c relating to the game, a trademark 20, etc. can be indicated on the exterior surface 38, as seen in FIG. 3. In this embodiment, information stored in the CD-ROM 17 is detected by a laser beam directed to the underside surface 34 of the transparent plastic substrate 31. The beam is reflected by the reflection layer 36 and detected by the optical pickup 21. The trademark 30 is formed using a group of pits on the optical detection surface 34, which is the undersurface of the CD-ROM 17, so that its shape can be visible therethrough. The optical pickup 21 is connected to the input/output interface 14b, and the input/output interface 14b is connected to the game control unit 11 through the judgement unit 26. The optical pickup 21 is radially moved with respect to the CD-ROM 17 on rotation from the read-in region 32a to the read-out region 32b to read program information and trademark information from the CD-ROM 17. Digitally-coded information is stored in a predetermined format in the program region 32 of the CD-ROM 17 and an image indication is visibly formed with pits in the predetermined region 30 of the CD-ROM 17. Accordingly it is necessary to program the CD-ROM control unit 29 beforehand that the predetermined region 30 stores information in a different format. The reading of trademark information from the predetermined region 30 is carried out in the middle of reading program information. When detection of the trademark information is started, detection and pick-up of the program information has already begun, and the game is on-going. As the optical pickup 21 moves from the read-in region 32a to the read-out region 32b, the trademark information is read sequentially, and the read trademark information is supplied to the game control unit 11 through the judgement unit 26. The judgement unit 26 stores the read trademark information picked up by the optical pickup 21, and when the reading of the trademark information is completed, it compares the stored trademark information with a reference trademark which has been stored beforehand in the judgement unit 26 to judge whether or not they agree with each other and it outputs an agreement or disagreement signal. Information as a reference which is stored beforehand in the judgement unit 26 is not limited to a trademark, and may be a specific indication such as a design, e.g. a game character, a tradename, or others which can be legally protected. It is preferable to use a specific indication that it is legally prohibited for an unauthorized person to use. The specific indication may be owned by the manufacturer of the game machine itself or licensed from another entity, and may be a combination of a plural number of the same indication or of different indications. The signal from the judgement unit 26 is supplied to the game control unit 11. When the signal is an agreement signal, security protection is released, and the program information is supplied to the game control unit, and the game continues. When the signal is a disagreement signal, security protection is not released, and transfer of the program information is stopped. When the game control unit 11 receives a disagreement signal, it conducts error processing by, e.g, outputting a warning signal such as "This disc cannot be used." onto the screen of a television unit 15, or outputting a stop signal for stopping the operation of the game machine 10. The operation of the game machine according to the second embodiment will be explained with reference to the flow chart of FIG. 9. First, a disc 17, such as a CD-ROM or other, which stores game software is inserted into the CD-ROM mount unit 18 and then a lid 19 is closed. The disc 17 is now mounted on the game machine 10. The game machine 10 can also reproduce music, information etc. from various CDs. A disk drive is actuated to rotate the disc, and the optical pickup 21 starts to read information (Step S1). Following the actuation of the disc, the optical pickup 21 reads TOC information in the innermost circumference of the disc. If the optical pickup 21 fails to read TOC information, it tries again (Step S2). TOC information is used to judge whether or not the mounted disc is a musical disc (Step S3). If the disc is a musical disc, Step S4 follows to reproduce the music. If the disc is other than a musical disc, Step S5 follows to judge whether or not a security check is necessary, i.e. whether the disc is a software disc which requires judgement as to whether the disc is authentic or counterfeit. If the security check is necessary, Step S6 follows. The optical pickup 21 advances to the program region 32 to read program information and the predetermined region 30 in which a specific trademark is indicated. The trademark information read from the predetermined region 30 is supplied to the judgement unit 26 and stored there. Trademark information as well as program information is concurrently read. Game processing I is conducted, and the game is started. When security checking is not necessary, Step S7 follows to judge whether or not the information stored in the disc is general software. When the reading of the trademark information is completed, data signals corresponding to the trademark information which have been supplied to and stored in the judgement unit 26 are compared with data signals corresponding to the previously stored specific trademark information in the judgement unit 26 (Step S8). When the information read from the predetermined region 30 on the disc is judged to agree with the specific trademark information previously stored in advance in the judgement unit 26, security is cleared, the program information is transmitted to the game control unit 11 and the game processing I is followed by game processing II (Step S9). When the information read from the predetermined region 30 is judged to disagree with the specific trademark information, security is not cleared and the execution of game processing I is stopped. Error processing, such as the display of a warning, or other, follows (Step S10). On the other hand, in Step S7, when the information stored in the disc is judged to be general software other than game software, Step Sll follows, and PLAY processing is conducted. For example, when the disc is a data information CD, data are displayed on the screen. When the disc does not hold general software, i.e. the disc holds software which is incompatible with the game machine 10, error processing, such as displaying a warning, or other, is conducted (Step S12). Thus, conventional security systems have utilized a process of judging agreement with a specific code or the like. In the game machine according to the present embodiment, the agreement of a visual indication such as a trademark or the like is judged for security. As the visual indication can be used an image such as a trademark which is widely recognized for its originality and invariably indicated on CD-ROMs. Such an image can effectively hinder counterfeiting, thereby enhancing security, If musical and data information CDs require security, the present invention is applicable in the same manner as the game software CD-ROMs, and can exclude counterfeits from the market. The present invention is not limited to the above-described embodiments. For example, in the above-described second embodiment, as shown in FIG. 10A, it is possible that a zone 30a in which no game program information is recorded is provided along the inner circumference of a disc, and a predetermined region 30 in which a specific trademark is indicated using a group of pits is provided in the zone 30a. In the second embodiment, as shown in FIG. 10B, a zone 30b in which no game program information is stored is provided along the outer circumference of a disc, and a predetermined region 30 in which a specific trademark is indicated using a group of pits is provided in the zone 30b. In the variations shown in FIGs. 10A and 10B, the zone 32 in which a game program is stored is separated from the zone 30a or the zone 30b. The zone 32, and the zone 30a or 30b which have different information storing modes or formats from each other are spaced apart from each other, thereby control of information reading from the information storage medium can be made simple. In the above-described variations, it is possible that the periphery of a game disc could be touched by dirty hands, and specific trademark information in the predetermined zone 30 could not be read. To avoid such occurrences, a plurality of predetermined regions are provided spaced from each other in the zone 30b, and a specific trademark may be indicated in each of the plural predetermined regions. In reading the specific trademark, when the trademark information in one of the predetermined regions 30 agrees with reference trademark information, security is cleared. Even if some of the plural predetermined regions 30 are stained by handling so much that the trademark information cannot be read, the rest of the regions 30 can still be read, ensuring higher accuracy. As shown in FIG. 10C, it is possible that a plurality of predetermined regions 30 are provided continuously or at a certain interval in, e.g., the zone 30b of the CD-ROM 17, and the same trademark is continuously indicated therein or different two types of specific indications may be indicated alternately. Further a plurality of predetermined regions 30 are formed to fill around the zone 30b. Such predetermined regions 30 can be provided in various combinations of numbers, intervals, etc. and a judging reference corresponding to the selected combination is stored in advance in the judgement unit 26, thereby further enhancing security. It is possible that the predetermined zone 30b in which a specific indication is to be indicated is provided, as shown in FIG. 10D, at an outer circumference of the read-out region 32b of the CD-ROM 17. Thus the predetermined zone 30b in which a specific indication is indicated can be clearly separated from the zone 30a in which program information is stored, whereby control of reading the information and the control of detecting the specific indication can be further facilitated. In the zone 30b, as seen in FIG. 10D, the visual image TRADE MARK "SEGA" and PRODUCED BY OR UNDER LICENSE FROM SEGA ENTERPRISES, LTD is formed using a group of pits in the predetermined zone 30b. A specific method of forming a specific indication with pits of the CD-ROM 17 will be explained with reference to FIG. 11. As shown in FIG. 11C, a specific indication, e.g. "SEGA", is formed visibly using a group of pits on the optical detection surface of the plastic substrate 31. Each dot constituting the letters of "SEGA" is formed using a group of pit arrays B enclosed by the broken line C in FIG. 11B, and the part at which dots constituting letters are not formed is formed with using a group of pit arrays A. The region enclosed by the broken line C can be visible by dots forming the letters with, e.g., 70 vertical tracks and 12 horizontal pit arrays. The group of pit arrays A are formed, as shown in FIG. 11A, with a unit which occupies a minimum pit area of the surface and the group of pit arrays B are formed with a unit which occupies a maximum pit area of the surface. In FIGs. 11A to 11C, a specific indication in the predetermined region 30 of the plastic substrate 31 is formed so as to be recognized as letters when seen from the optical detection surface, but may be formed so as to be recognized as letters when seen from the surface opposite to the optical detection surface. A specific indication to be used in the security check can be any indication, such as, in addition to a trademark, a graphic design of game characters or others, a tradename, an indication mark of a company or others, which can be identified to effectively exclude counterfeits from the market. Namely, it is preferred that a specific indication is an indication by which legal action can be taken against a person who uses the indication without authorization. A specific indication can be one which is made by its owner or licensed under a license agreement. The same plural specific indications, or combinations of plural different specific indications may be used. A specific indication to be formed in the predetermined region of the CD-ROM 17 is formed in a visible shape and size and may be formed in, for example, a sector along the outer circumference of the CD-ROM 17.

Claims: An electronic device (10,29) comprising an authentication system wherein the authenticity with respect to the electronic device of an optical disk (17) is checked, wherein the authentication system comprises reference information stored in advance in the electronic device, a disk mounting means (18) on which the optical disk (17) is to be mounted, detection means (21,22) for detecting authentication information from the optical disk (17), and comparison means (26) for comparing the detected authentication information with the reference information, wherein the said detection means (21,22) are arranged to detect a specific indication as the authentication information from a predetermined region of the optical disk (17) ; characterized in that the specific indication is also recognizable by the naked human eye as a proprietary indication, the proprietary indication being of a nature that unauthorized use of the proprietary indication is legally prohibited. An electronic device (10,29) according to claim 1, wherein the electronic device comprises a game control means (11) and the optical disk (17) comprises an information region (32) storing a game program, characterized in that the electronic device judges that the information storage medium (17) is authentic to the electronic device when the authentication information detected from the specific indication agrees with the reference information. An electronic device (10,29) according to claim 1 or 2, further comprising operational control means (11) which controls an operational state of the electronic device (10) in accordance with the result of the comparison of the detected information with the reference information. An electronic device (10) according to claim 3, wherein operation of the electronic device stops when the detected information detected from the predetermined region (20,30) does not agree with the reference information. An electronic device (10,29) according to any of claims 1 to 4, further comprising warning display means for displaying a predetermined warning message on a monitor (15) when detected information detected from the predetermined region (20,30) does not agree with the reference information. An electronic device (10,29) according to any of claims 1 to 5, wherein the optical disk (17) comprises a first region (32) storing a game program and a second region (20,30) on which the specific indication is formed, characterized in that both the specific indication and the game program are detected by the same optical detection means (21). An electronic device (10,29) according to any of claims 1 to 5, wherein the electronic device comprises a first optical detection means (21) and a second optical detection means (22), the optical disk (17) comprises a first surface (34) and a second surface (38) disposed oppositely to the first surface, the first optical detection means (21) being disposed so as to face the first surface (34) to optically read a game program stored in the optical disk (17), characterized in that the second optical detection means (22) is disposed so as to face the second surface (38) on which the specific indication is formed. An information storage medium (17) comprising an optical disk containing a first region (32) in which software information is stored so that when the optical disk is mounted on an electronic device (29), the software information is optically read by detection means (21) provided in the electronic device, characterized in that the optical disk further comprises a second region (30) disposed in a region different from the said first region (32), the second region (30) contains a specific indication formed by means of pits so that the specific indication formed by means of pits is detectable by the said detection means (21) and can be judged as authentication information by comparing the information detected from the specific indication with a reference information stored in advance in the electronic device (29) as well as recognizable by the naked human eye as a proprietary indication, the proprietary indication being of a nature that unauthorized use of the proprietary indication is legally prohibited. An information storage medium (17) according to claim 8, wherein the said second region (30) is disposed at an inner circumference of the first region (32). An information storage medium (17) according to claim 8, wherein the said second region (30) is disposed at an outer circumference of the first region (32). An information storage medium (17) according to any of claims 8 to 10, characterized in that a plurality of the specific indications are formed. An information storage medium (17) according to any of claims 8 to 11, characterized in that pits (B) constituting visible portions of said specific indication in the second region (30) are relatively larger in area than pits (A) which occupy portions not visible. An information storage medium (17) according to any of claims 8 to 12, wherein the specific indication is the trademark "SEGA".

Inventors: KITAHARA ATSUSHI, KITAHARA, ATSUSHI
Applicants: SEGA ENTERPRISES KK, SEGA ENTERPRISES, LTD.
Application year: 1994
Main classification: G11B7
IPC codes: G11B23, A63F13, G11B20, H04N5